@article {11635, title = {Comparison Between Ray-Tracing Simulations and Bi-Directional Transmission Measurements on Prismatic Glazing}, journal = {Solar Energy}, volume = {74}, number = {2}, year = {2003}, month = {02/2003}, pages = {157-173}, chapter = {157}, abstract = {

Evaluation of solar heat gain and daylight distribution through complex window and shading systems requires the determination of the bi-directional transmission distribution function (BTDF). Measurement of BTDF can be timeconsuming, and inaccuracies are likely because of physical constraints and experimental adjustments. A general calculation methodology, based on more easily measurable component properties, would be preferable and would allow much more flexibility. In this paper, measurements and calculations are compared for the specific case of prismatic daylight-redirecting panels. Measurements were performed in a photogoniometer equipped with a digital-imaging detection system. A virtual copy of the photogoniometer was then constructed with commercial ray-tracing software. For the first time, an attempt is made to validate detailed bi-directional properties for a complex system by comparing an extensive set of experimental BTDF data with ray-tracing calculations. The results generally agree under a range of input and output angles to a degree adequate for evaluation of glazing systems. An analysis is presented to show that the simultaneously measured diffuse and direct components of light transmitted by the panel are properly represented. Calculations were also performed using a more realistic model of the source and ideal model of the detector. Deviations from the photogoniometer model were small and the results were similar in form. Despite the lack of an absolute measurement standard, the good agreement in results promotes confidence in both the photogoniometer and in the calculation method.\ 

}, doi = {10.1016/S0038-092X(03)00115-4}, author = {Marilyn Andersen and Michael D. Rubin and Jean-Louis Scartezzini} } @article {11601, title = {Calculation of Thermodynamic, Electronic, and Optical Properties of Monoclinic Mg2NiH4}, journal = {Journal of Applied Physics}, volume = {91}, number = {8}, year = {2002}, month = {04/2002}, pages = {4879-4885}, chapter = {4879}, abstract = {

Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT\ Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic\ Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT\ Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

}, doi = {10.1063/1.1454206}, author = {Whittier R. Myers and Lin-Wang Wang and Thomas J. Richardson and Michael D. Rubin} } @conference {11636, title = {Comparison of AIN Films Grown by RF at Magnetron Sputtering and Ion-Assisted Molecular Beam Epitaxy}, booktitle = {Materials Research Society}, volume = {300}, year = {1993}, month = {04/1993}, address = {San Francisco, CA}, abstract = {

Crystalline aluminum nitride (AlN) thin films were formed on various substrates by using RF magnetron sputtering of an A1 target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AlN/(111) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 {\textdegree}C, while the crystallinity of AlN/(0001) Al2O3 samples improved from 700 to 850 {\textdegree}C. The optical absorption characteristics of the AlN/(0001) Al2O3 films as grown by both deposition methods revealed a decrease in sub-band gap absorption with increased substrate temperature.

}, author = {James S. Chan and T.C. Fu and Nathan W. Cheung and Jennifer T. Ross and Nathan Newman and Michael D. Rubin} }